Iida Hidehiro, Eberl Stefan, Kim Kyeong-Min, Tamura Yoshikazu, Ono Yukihiko, Nakazawa Mayumi, Sohlberg Antti, Zeniya Tsutomu, Hayashi Takuya, Watabe Hiroshi
Department of Investigative Radiology, National Cardiovascular Center Research Institute, Fujishiro-dai, Suita City, Osaka 565-8565, Japan.
Eur J Nucl Med Mol Imaging. 2008 May;35(5):896-905. doi: 10.1007/s00259-007-0654-4. Epub 2008 Jan 15.
201Tl has been extensively used for myocardial perfusion and viability assessment. Unlike 99mTc-labelled agents, such as 99mTc-sestamibi and 99mTc-tetrofosmine, the regional concentration of 201Tl varies with time. This study is intended to validate a kinetic modelling approach for in vivo quantitative estimation of regional myocardial blood flow (MBF) and volume of distribution of 201Tl using dynamic SPECT.
Dynamic SPECT was carried out on 20 normal canines after the intravenous administration of 201Tl using a commercial SPECT system. Seven animals were studied at rest, nine during adenosine infusion, and four after beta-blocker administration. Quantitative images were reconstructed with a previously validated technique, employing OS-EM with attenuation-correction, and transmission-dependent convolution subtraction scatter correction. Measured regional time-activity curves in myocardial segments were fitted to two- and three-compartment models. Regional MBF was defined as the influx rate constant (K(1)) with corrections for the partial volume effect, haematocrit and limited first-pass extraction fraction, and was compared with that determined from radio-labelled microspheres experiments.
Regional time-activity curves responded well to pharmacological stress. Quantitative MBF values were higher with adenosine and decreased after beta-blocker compared to a resting condition. MBFs obtained with SPECT (MBF(SPECT)) correlated well with the MBF values obtained by the radio-labelled microspheres (MBF(MS)) (MBF(SPECT) = -0.067 + 1.042 x MBF(MS), p < 0.001). The three-compartment model provided better fit than the two-compartment model, but the difference in MBF values between the two methods was small and could be accounted for with a simple linear regression.
Absolute quantitation of regional MBF, for a wide physiological flow range, appears to be feasible using 201Tl and dynamic SPECT.
201铊已被广泛用于心肌灌注和存活评估。与99m锝标记的药物（如99m锝- sestamibi和99m锝- tetrofosmine）不同，201铊的局部浓度随时间变化。本研究旨在验证一种动力学建模方法，用于使用动态单光子发射计算机断层显像（SPECT）对局部心肌血流量（MBF）和201铊的分布容积进行体内定量估计。
使用商用SPECT系统对20只正常犬静脉注射201铊后进行动态SPECT检查。7只动物在静息状态下进行研究，9只在腺苷输注期间进行研究，4只在给予β受体阻滞剂后进行研究。使用先前验证的技术重建定量图像，采用有序子集期望最大化（OS-EM）算法进行衰减校正，并进行基于传输的卷积减法散射校正。将心肌节段中测量的局部时间-活性曲线拟合到二室和三室模型。局部MBF定义为流入速率常数（K(1)），并对部分容积效应、血细胞比容和有限的首过提取分数进行校正，然后与放射性标记微球实验确定的值进行比较。
局部时间-活性曲线对药物应激反应良好。与静息状态相比，腺苷刺激时定量MBF值更高，β受体阻滞剂给药后降低。SPECT获得的MBF（MBF(SPECT)）与放射性标记微球获得的MBF值（MBF(MS)）相关性良好（MBF(SPECT) = -0.067 + 1.042 × MBF(MS)，p < 0.001）。三室模型比二室模型拟合更好，但两种方法之间MBF值的差异较小，可用简单线性回归解释。
使用201铊和动态SPECT对较宽生理血流范围内的局部MBF进行绝对定量似乎是可行的。
